Every September there are a handful of days when the daddy longlegs are being blown onto the water and the trout throw their usual caution away entirely. It is the most fun you can have with a dry fly on a stillwater, and it is worth arranging your fishing around.
Why it happens
Crane flies hatch out of grassland in late summer and autumn, and they are hopeless fliers. Any decent breeze picks them up off the bank and dumps them on the water. They are large, they are helpless, and they represent a very substantial mouthful for a trout.
Once a few have blown on and been eaten, the fish start looking up for them. That is the point where a well-fished imitation gets absolutely hammered.
You need wind, and you need the right bank
This is the bit people get wrong. A flat calm September day will produce almost no daddies on the water. You want a decent breeze, and you want to be on the bank it is blowing onto, or fishing the water it is blowing across.
The best conditions are a warm, blustery day with the wind coming off grassland or trees. If the bank behind you is rough pasture and the wind is in your face, you are in exactly the right place.
People instinctively fish the sheltered bank because casting is easier. Fish the awkward one.
The mistake: moving the fly
A real daddy on the water does one of two things. It sits there completely still, or it makes a brief, panicky struggle and then stops.
What it never does is move steadily across the surface. And yet the commonest thing I see is anglers slowly retrieving a daddy pattern, which looks like nothing in nature and which trout refuse.
Cast it, and leave it. Let it sit. If nothing has happened after a minute or so, give it the tiniest twitch, just enough to make the legs move, then leave it again. That twitch is often what triggers the take.
Hold your nerve on the take
The other classic error is striking too fast. A trout taking a daddy off the top often comes up slowly and deliberately, and it is a big enough mouthful that they take their time about it.
If you strike the instant you see the rise you will pull it out of the fish’s mouth. Wait until the fish has turned down and the line draws tight, then lift firmly. Saying “God save the Queen” before you lift is the old advice and it is not a joke, it is about the right pause.
Patterns and setup
Almost any reasonable daddy pattern will do. Detached body or dubbed, knotted pheasant tail legs, a decent hackle to keep it up in a ripple. Carry a couple of sizes and both a well-hackled version for choppy water and a sparser one for calmer conditions.
Fish it on a floating line and a long leader, twelve to fifteen feet, tapered down to about four or five pound. Degrease the last section of the leader so it sinks and does not leave a shine on the surface.
One fly is usually enough. If you want to hedge, a daddy on the point with a smaller dry on a dropper works well.
When it is not happening
Some September days there just are not any daddies. If you are not seeing them on the water and not seeing fish looking up, do not force it. Switch to a fry pattern or a nymph and come back to the daddy when conditions change.
Equally, do not give up on it too early in the day. Daddy fishing often improves through the afternoon as the wind picks up and the day warms.
The session
Warm, windy September afternoon. Walk to the bank the wind is blowing onto, even if it is the hard one to cast from. Single daddy on a long leader, cast out, and do nothing. Watch it. It is the most relaxed and the most exciting way to fish a reservoir at the same time.

Sarah Marsh came to fly fishing through her father, who kept a rod on a small syndicate water in Devon. She spent her teens fishing stocked reservoirs and gradually worked her way toward wild fish on moving water – first on rain-fed freestone rivers in Wales, then on the Hampshire chalk streams she now considers home water.
She holds a level 2 APGAI fly casting qualification and guides informally on the River Test and, from June to September, on a private beat on the River Tay for Atlantic salmon. Her personal best brown trout came from the Itchen at 4lb 1oz; she’d sooner not talk about the salmon that came off at the net last August.
At The River Bend, Sarah writes the game fish species guides, fly fishing technique articles, and the legal content covering trout and salmon regulations.
Covers: Brown trout, rainbow trout, sea trout, Atlantic salmon, fly fishing, chalk streams, Scottish rivers, close season and regulation articles